This invention relates generally to methods and apparatus for repairing soft tissue arthroscopically, and more particularly to methods and apparatus for passing suture through soft tissue.
There are many procedures, such as capsular plication, Bankart lesion repairs, or reconstruction of labral tissue to the glenoid rim, in which a practitioner needs to secure tissue in close contact with bone. Suture is passed through soft tissue, the bone surface is roughened, and when tissue is pulled into intimate contact, the body's healing response will fuse the tissue and bone together.
Such procedures are often accomplished by implanting an anchor, pre-loaded with a strand of suture, into a hole drilled in the bone at a desired anchor location. One or both of the suture ends are then passed through soft tissue at the desired location, the tissue is pulled close to the bone at the anchor site, and the suture is secured to the anchor by tying a knot.
There are many suture passing devices on the market today, which are intended to pass suture through soft tissue. Some are designed for specific locations—i.e. devices like the Arthrex VIPER and SCORPION, which are designed to grasp rotator cuff tissue and pass a suture perpendicularly through it. Using these types of devices, the surgeon captures the edge of the tissue in the jaws of a grasper, which stabs a needle, carrying suture, through the rotator cuff tissue. The suture is then retrieved with a grasper. However, this device cannot pass suture multiple times without reloading the device. Also, since they are optimized for rotator cuff tissue, they cannot reach many of the areas within the gleno-humeral joint space.
More general suture passer designs consist of a needle bent into several curved shapes at the sharp end. The curves differ in angle of bend, direction of curve, and shape of curve, to allow the surgeon to reach as many locations within the joint as possible. The surgeon plunges the tip of the needle into tissue at one location and back out of the tissue at another. Suture is then “shuttled” through the needle. The needle is removed and the suture remains, passing through the tissue at the desired location.
The Conmed Linvatec Spectrum suture passing device is a general purpose suture passing device that comes with several different suture hook variations to allow for access to multiple locations within the joint. This device can use monofilament suture for shuttling or a dedicated suture lasso. In an effort to eliminate suture shuttling, Conmed has recently released the Spectrum MVP product. This device adds a tube which runs alongside the curved needle. The curved needle is passed through the tissue. A nitinol suture snare is then deployed from inside the tip of the curved needle, which opens to form a loop. A piece of suture, which is loaded onto the tip of the straight tube, is pushed forward and through the loop by a nitinol push-rod. The snare is closed around the suture and push-rod, capturing the suture. The curved needle is then pulled back through the tissue, bringing the suture along with it and out of the joint. Although this new device eliminates the shuttling step, it must be passed completely through the tissue (in order to deploy the nitinol snare) and it can only make one suture pass at a time. It must be removed from the joint and reloaded with suture for each pass. Also, if the joint space is small, the nitinol loop may not be able to fully open or may get pushed to the side. In this case, it may no longer line up with the nitinol push-rod and be able to capture the suture.
There are several methods of “shuttling” suture once the needle is passed through the tissue. Since it is difficult to push suture down the long needle, often a “suture shuttle” is passed down the shaft and out the end of the needle where it is grasped by an arthroscopic grasper, often introduced into the joint space through another portal. One end of the suture shuttle is pulled out of the joint space, attached to a free end of the suture that will remain in the body, then pulled back through the tissue. This pulls the suture back through the hole, where it is then used to secure the tissue to the desired location, often an anchor. Common suture shuttles are monofilament suture (which is tied around the high-strength suture to pull it back through the tissue), monofilament suture loops to snare the suture, or dedicated snares made of nitinol wire.
One of the most difficult steps in passing suture through soft tissue with existing devices is piercing the needle completely through the tissue. Piercing the needle tip into the tissue is usually not difficult. However, getting the tip of the needle back out of the tissue so that the suture shuttle can be passed out of the end can be difficult, especially if the tissue is very soft. This is often the case in the inferior capsule of the shoulder. An important step in reducing laxity of the shoulder, called capsular plication or capsular shift, is passing suture through capsular tissue inferior to the glenoid. This tissue is often very soft and does not provide enough tension to resist the needle and allow the tip to pierce back out of the tissue.
Arthrex, TAG, and several other companies also make suture passers which operate slightly differently, and do not require suture shuttling. Arthrex's version, the Birdbeak, resembles a sharply pointed set of suture graspers. The device is pierced through the tissue, grasps suture already in the joint space (usually attached to an anchor), and pulls the suture back through the tissue. These devices do not require suture shuttling and can, theoretically, pull sutures through different locations without removing the device from the joint space. However, mobility of the device is severely limited once it has been pierced through the tissue. This requires the suture to be in the correct location to be grasped. This is often accomplished by holding and manipulating the suture with a grasper placed into the joint through a second working portal.